With regard to employment of retraction mechanics, it is well known that free tipping tooth movement is arguably the most efficient type of tooth movement in orthodontics, inasmuch as with such tooth movement the teeth move faster with the least amount of force. During retraction mechanics there may be retraction of incisors, cuspids or bicuspids, and where the teeth move faster with lighter forces applied during the treatment. It is also known that lighter forces significantly reduce the possibility of root resorption of orthodontically induced tooth movements. Further, lighter forces enhance the success of differential force systems, inasmuch as during retraction mechanics, forces are applied between larger posterior anchor teeth, such as molars or premolars, and anterior teeth, such as incisors, bicuspids or bicuspids. With lighter forces the positions of these anchor teeth will essentially be undisturbed during retraction of incisors, cuspids or bicuspids.
Heretofore, it has been well known to employ retraction mechanics for moving teeth in the edgewise and straight-wire techniques with brackets having rotatable archwire engaging members that may allow to an extent tipping and uprighting, such as disclosed in U.S. Pat. Nos. 4,867,678 and 5,302,121. However, with respect to these bracket appliances, the increased frictional resistance during retraction mechanics extends the time needed to complete the retraction goals, and the time of patient treatment requires heavier forces which may cause root resorption, as well as adversely affecting the comfort of the patient.